This invention relates to a trimmer and more particularly to an edge gum trimmer unit for use in trimming side edges of excess rubber from rubber coated fabric.
In applying a thin coat of rubber onto moving parallel strands of fabric by means of calender rolls, a surplus of rubber is used to assure the coating of the entire width of the fabric including the side marginal edges. In order to provide a finished coated fabric which requires cutting and the subsequent splicing of the side edges to fabricate the bias ply fabric, the calendered ply stock of coated fabric must have its parallel side edges trimmed cleanly and evenly close to edge cords to assure a consistent spacing of rubber and the strands of fabric. In calendering fabric, there is a tendency for the edge cords to spread or move apart from their initial position. In addition, there is a tendency for the fabric along with its cords to shift as a unit laterally as it is unwound from a supply roll. Efforts to obtain a smooth, evenly coated edge have included sensing means to position the edge trimmer as in U.S. Pat. No. 3,008,864, however, there is a lag in the response of controls that can magnify the amount of edge gum. U.S. Pat. No. 3,238,831 has applied to a lateral pressure to the knife to maintain an even pressure. The present invention is an improvement over the latter patent by providing a structure which compensates for the angular adjustment of the guide rods for the carriage which carries the trimming knives to assure for a cut that is normal to the surface of the fabric even though the trim knife is biased downwardly toward the lateral edge to be trimmed.